Epi Profile Section 5 - Recent Transmission

The CDC estimates that in 2019, 16.4% of TB cases in Texas were attributed to recent transmission, compared to 12.5% of cases nationally.[1] The CDC defines recent TB transmission as occurring if a likely source case[2] can be identified in a person who:

  • has the same Mycobacterium tuberculosis genotype;
  • has an infectious form of TB disease;
  • resides within ten miles of the index TB case;
  • is ten years of age or older; and
  • was diagnosed within two years before the index TB case

Of the 16.4% recent transmission cases, 6.9% were attributed to extensive recent transmission2. Extensive recent transmission is defined as occurring when a TB case meets the criteria above for recent transmission, and the case belongs to a likely transmission chain of six or more cases.[1]

The infectiousness of a patient can contribute to recent transmission. A positive acid-fast bacilli (AFB) sputum smear indicates infectiousness and chest radiographic results with cavitary lesions indicate advanced TB disease.

In 2019, 20% of TB cases in Texas had a cavitary chest radiograph regardless of AFB smear result, 18.6% had a positive AFB smear and non-cavitary chest radiograph, and 14.8% had a cavitary chest radiograph and a positive AFB smear.



1. Centers for Disease Control and Prevention (CDC). Reported Tuberculosis in the United States, 2019. Atlanta, GA: US Department of Health and Human Services, CDC; 2020.

2. France AM, Grant J, Kammerer JS, Navin TR. A field-validated approach using surveillance and genotyping data to estimate tuberculosis attributable to recent transmission in the United States. Am J Epidemiol 2015; 182: 799-807.

Table of Contents | An Overview of Tuberculosis in Texas | Geographic Distribution of Tuberculosis in Texas | Affected Populations | Case Diagnosis | Recent Transmission | Mortality | Risk Factors Associated with Tuberculosis | Drug Resistant TB | Public Health Follow-Up Outcomes | Reporting Requirements | References